Plain bearing

Abstract

A cavitation erosion resistant plain bearing comprising a steel backing, a sintered bronze interlayer and a lining of PTFE filled with 1 to 50% by volume of an ionic fluoride of low aqueous solubility.

I claim: 
     
       1. A plain bearing comprising a metal backing, a sinter layer on said metal backing and a bearing layer on said sinter layer, said bearing layer comprising a surface layer of polytetrafluoroethylene (PTFE) including 1 to 50% by volume of an ionic fluoride selected from the group consisting of CaF 2 , MgF 2 , SrF 2  and mixtures thereof precipitated from an aqueous solution and having a solubility in water which is less than 0.5 g/cm 3  at 18° C., the ionic fluoride being in a finely divided form in the PTFE, the particle size being in the range from 0.01 to 10 microns. 
     
     
       2. A bearing according to claim 1 wherein said backing is of steel. 
     
     
       3. A bearing according to claim 2 wherein said sinter layer is sintered bronze. 
     
     
       4. A bearing according to claim 1 wherein said fluoride is a fluoride selected from the group consisting of CaF 2 , MgF 2  and SrF 2 . 
     
     
       5. A bearing according to claim 4 wherein said surface layer further incorporates metallic lead. 
     
     
       6. A plain bearing as described in claim 1 wherein the particle size of said fluoride is in the range of 0.1 to 1 micron. 
     
     
       7. A plain bearing according to claim 1 wherein said fluoride is a combination of two or more of the fluorides selected from the group consisting of CaF 2 , MgF 2  and SrF 2 . 
     
     
       8. A plain bearing according to claim 1 wherein said fluoride is CaF 2 . 
     
     
       9. A plain bearing according to claim 1 wherein said fluoride is CaF 2  having a particle size in the range of 0.1 to 1 micron. 
     
     
       10. A bearing according to claim 1 wherein the ionic fluoride is precipitated CaF 2 . 
     
     
       11. A bearing according to claim 1 wherein the ionic fluoride is precipitated CaF 2  and has a particle size in the range of 0.1 to 1 micron. 
     
     
       12. A plain bearing comprising a metal backing, a sinter layer on said metal backing and a bearing layer on said sinter layer, said bearing layer comprising a surface layer of polytetrafluoroethylene containing from 1 to 50 volume percent of at least one ionic fluoride selected from the group consisting of CaF 2 , MgF 2 , SrF 2  and mixtures thereof having a water solubility not greater than 0.05 grams per cubic centimeter at 18° C. and a particle size in the range from 0.01 to 10 microns. 
     
     
       13. A plain bearing according to claim 12 wherein said fluoride comprises CaF 2 . 
     
     
       14. A plain bearing according to claim 13 wherein said fluoride has a particle size in the range from 0.1 to 1 micron. 
     
     
       15. A plain bearing according to claim 12 wherein the particle size of said fluoride is in the range from 0.1 to 10 microns. 
     
     
       16. A plain bearing according to claim 12 wherein the particle size of said fluoride is in the range from 0.1 to 1 micron. 
     
     
       17. A plain bearing according to claim 12 wherein said fluoride is a combination of two or more of the fluorides selected from the group consisting of CaF 2 , MgF 2 , SrF 2  and mixtures thereof.